Initial circuits plugin work.

plugins/circuits/src/Terminal.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include "CircuitElement.h"
+
+#include <string>
+
+class Wire;
+
+class Terminal : public CircuitElement
+{
+public:
+    enum class TerminalType
+    {
+        INPUT,
+        OUTPUT
+    };
+
+    Terminal(TerminalType type, const std::string& label = {});
+
+    Wire* getConnection() const;
+
+    Type getType() const override
+    {
+        return mType == TerminalType::INPUT ? Type::INPUT_TERMINAL : Type::OUTPUT_TERMINAL;
+    }
+
+    void setConnection(Wire* connection);
+
+private:
+    std::string mLabel;
+    bool mValue{ false };
+    TerminalType mType;
+    Wire* mConnection{ nullptr };
+};
+using TerminalPtr = std::unique_ptr<Terminal>;